uinput-filter-mouse - program to filter and rewrite uinput events

.gitignore

/uinput-filter-mouse
/config.h

config.h.sample

#define UPSTREAM_UINPUT_DEVICE "/dev/input/by-id/usb-Logitech_G700_Laser_Mouse_37ADAF750037-event-mouse"

Makefile

uinput-filter-mouse: Makefile uinput-filter-mouse.c config.h
	gcc -o $@ $@.c

config.h:
	@echo "Copy and edit \`config.h.sample' to \`config.h' first."
	@exit 1

install:
	install uinput-filter-mouse /usr/local/bin/
	install -m 644 uinput-filter-mouse.service /etc/systemd/system

uinput-filter-mouse.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/input.h>
#include <linux/uinput.h>

#include "config.h"

#define die(str, args...) do { \
		perror(str); \
		exit(EXIT_FAILURE); \
	} while(0)

int
main(int argc, char* argv[])
{
	int                    fdo, fdi;
	struct uinput_user_dev uidev;
	struct input_event     ev;
	int                    i;

	//if(argc != 2) die("error: specify input device");

	fdo = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
	if(fdo < 0) die("error: open");

	//fdi = open(argv[1], O_RDONLY);
	fdi = open(UPSTREAM_UINPUT_DEVICE, O_RDONLY);
	if(fdi < 0) die("error: open");

	if(ioctl(fdi, EVIOCGRAB, 1) < 0) die("error: ioctl");

	if(ioctl(fdo, UI_SET_EVBIT, EV_SYN) < 0) die("error: ioctl");
	if(ioctl(fdo, UI_SET_EVBIT, EV_KEY) < 0) die("error: ioctl");
	if(ioctl(fdo, UI_SET_EVBIT, EV_REL) < 0) die("error: ioctl");
	if(ioctl(fdo, UI_SET_EVBIT, EV_MSC) < 0) die("error: ioctl");

	for(i = 0; i < KEY_MAX; ++i)
		if(ioctl(fdo, UI_SET_KEYBIT, i) < 0) die("error: ioctl");
	for(i = 0; i < REL_MAX; ++i)
		if(ioctl(fdo, UI_SET_RELBIT, i) < 0) die("error: ioctl");

	memset(&uidev, 0, sizeof(uidev));
	snprintf(uidev.name, UINPUT_MAX_NAME_SIZE, "my-uinput-filter");
	uidev.id.bustype = BUS_USB;
	uidev.id.vendor  = 0x1;
	uidev.id.product = 0x1;
	uidev.id.version = 1;

	if(write(fdo, &uidev, sizeof(uidev)) < 0) die("error: write");
	if(ioctl(fdo, UI_DEV_CREATE) < 0) die("error: ioctl");

	while(1)
	{
		if(read(fdi, &ev, sizeof(struct input_event)) < 0)
			die("error: read");

		//printf("Got event! type=%d code=%d value=%d\n", ev.type, ev.code, ev.value);
		//ev.time.tv_sec = 0;
		//ev.time.tv_usec = 0;

		if (ev.type == EV_KEY)
		{
			int key = ev.code;
			if (key == BTN_EXTRA || key == BTN_SIDE)
			{
				ev.code = KEY_LEFTMETA;
				if(write(fdo, &ev, sizeof(struct input_event)) < 0)
				    die("error: write");

				if (key == BTN_EXTRA)
					ev.code = BTN_LEFT;
				if (key == BTN_SIDE)
					ev.code = BTN_RIGHT;
				if(write(fdo, &ev, sizeof(struct input_event)) < 0)
					die("error: write");
			}
		}

		if(write(fdo, &ev, sizeof(struct input_event)) < 0)
			die("error: write");
	}

	if(ioctl(fdo, UI_DEV_DESTROY) < 0) die("error: ioctl");

	close(fdi);
	close(fdo);

	return 0;
}

uinput-filter-mouse.service

[Unit]
Description=uinput mouse filter

[Service]
ExecStart=/usr/local/bin/uinput-filter-mouse
Restart=always

[Install]
WantedBy=default.target

I'm don't have a lot of experience in C, so I was wondering, can you help me out a little bit?

The button code I'm trying to map is 0x118. I have gotten it to work with binding it to KEY_LEFTMETA + BTN_LEFT.

I would also like to bind it to BTN_RIGHT when leftmeta is already pressed. However, it doesn't seem to work. Any pointers what I'm doing wrong?

Here's the modified code.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/input.h>
#include <linux/uinput.h>

#include "config.h"

#define die(str, args...) do { \
        perror(str); \
        exit(EXIT_FAILURE); \
    } while(0)

int
main(int argc, char* argv[])
{
    int                    fdo, fdi;
    struct uinput_user_dev uidev;
    struct input_event     ev;
    int                    i;
    int                    mod_pressed;

    //if(argc != 2) die("error: specify input device");

    fdo = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
    if(fdo < 0) die("error: open");

    //fdi = open(argv[1], O_RDONLY);
    fdi = open(UPSTREAM_UINPUT_DEVICE, O_RDONLY);
    if(fdi < 0) die("error: open");

    if(ioctl(fdi, EVIOCGRAB, 1) < 0) die("error: ioctl");

    if(ioctl(fdo, UI_SET_EVBIT, EV_SYN) < 0) die("error: ioctl");
    if(ioctl(fdo, UI_SET_EVBIT, EV_KEY) < 0) die("error: ioctl");
    if(ioctl(fdo, UI_SET_EVBIT, EV_REL) < 0) die("error: ioctl");
    if(ioctl(fdo, UI_SET_EVBIT, EV_MSC) < 0) die("error: ioctl");

    for(i = 0; i < KEY_MAX; ++i)
        if(ioctl(fdo, UI_SET_KEYBIT, i) < 0) die("error: ioctl");
    for(i = 0; i < REL_MAX; ++i)
        if(ioctl(fdo, UI_SET_RELBIT, i) < 0) die("error: ioctl");

    memset(&uidev, 0, sizeof(uidev));
    snprintf(uidev.name, UINPUT_MAX_NAME_SIZE, "my-uinput-filter");
    uidev.id.bustype = BUS_USB;
    uidev.id.vendor  = 0x1;
    uidev.id.product = 0x1;
    uidev.id.version = 1;

    if(write(fdo, &uidev, sizeof(uidev)) < 0) die("error: write");
    if(ioctl(fdo, UI_DEV_CREATE) < 0) die("error: ioctl");

    mod_pressed = 0;
    while(1)
    {
        if(read(fdi, &ev, sizeof(struct input_event)) < 0)
            die("error: read");

        //printf("Got event! type=%d code=%d value=%d\n", ev.type, ev.code, ev.value);
        //ev.time.tv_sec = 0;
        //ev.time.tv_usec = 0;

        if (ev.type == EV_KEY)
        {
            if (ev.code == KEY_LEFTMETA)
            {
                mod_pressed = ev.value; // 0 if released, 1 if pressed.
            }
            
            else if (ev.code == 0x118)
            {
                if (mod_pressed)
                {
                    ev.code = BTN_RIGHT;
                }
                
                else
                {
                    ev.code = KEY_LEFTMETA;
                    if(write(fdo, &ev, sizeof(struct input_event)) < 0)
                        die("error: write");
        
                    ev.code = BTN_LEFT;
                }
            }
        }

        if(write(fdo, &ev, sizeof(struct input_event)) < 0)
            die("error: write");
    }

    if(ioctl(fdo, UI_DEV_DESTROY) < 0) die("error: ioctl");

    close(fdi);
    close(fdo);

    return 0;
}

@aksel Sorry for the late reply, I don't think I saw your message until now. I'm not quite clear on what you're trying to achieve - you want to translate key 0x118 to KEY_LEFTMETA + BTN_LEFT, but also translate KEY_LEFTMETA + 0x118 to BTN_RIGHT?

I haven't seen your reply until now

Gist stuff doesn't trigger a notification, apparently

But yeah, that was what I wanted to do.

0x118 -> KEY_LEFTMETA + BTN_LEFT (for moving floating)
KEY_LEFTMETA + 0x118 -> KEY_LEFTMETA + BTN_RIGHT (for resizing)

I have since gotten a new mouse, that has an extra button that I have bound to resizing. But for future reference, how
would I have achieved the other thing?

Hahaha, how to contact you... Maybe a ping @CyberShadow will work?

Gist stuff doesn't trigger a notification, apparently

It seems to be a long-standing omission: isaacs/github#21

These's apparently a third-party service: https://giscus.co/

But for future reference, how
would I have achieved the other thing?

Your code looks correct... I don't know why it wouldn't work.

I would try debugging it with more logging in the program, and looking at what ends up in xev.